Radiolocation is an established technique for determining the location of a target device. The target is provided with a radio tag that will transmit beacon signals to one or more remote detectors, or alternatively receive beacon signals from one or more remote radio transmitters, at periodic intervals. By detecting the beacons signals, it is possible to infer information about the target location.
Conventional radiolocation methods exploit measurements of the angle of arrival (AoA) or time of arrival (ToA) or perform a multi-lateration or intersection test (such as triangulation) to compute the most likely location of the target. The most likely candidate location then has to be selected by a selection process which can consider the prediction of the likely movement of the target from prior estimates. However, the presence of propagation anomalies such as multi-path reflection, interference and shadowing can result in spurious location candidates. These anomalies cannot be easily eliminated if they appear equally likely to be valid. In addition, some measurements may have unknown or inaccurate reference location estimates. Hence, the multi-lateration or intersections will also result in the propagation of the inaccurate or unknown location estimates.